Cryogenic surgical instrument

ABSTRACT

An apparatus for directly converting a gas into a liquid to lower the temperature of a cryogenic surgical instrument. A tube with a linear entrance and exit section is helically wound around a core. A thermal conductive member surrounds the tube between the entrance and exit sections. A gas under pressure is connected to the entrance section of the tube. A sleeve with a closed end frictionally engages and surrounds the thermal conductive member to form a closed chamber adjacent the exit section of the tube. The pressurized gas is throttled upon leaving the exit section causing the temperature in the chamber to be lowered to between 80* to -250* C causing the gas to liquefy. A path through the thermal conductive member from the chamber to the atmosphere will permit thermal energy in the throttled gas to be dissipated to the pressurized gas in the tube. The liquefied gas in the chamber will correspondingly cool the closed end of the sleeve allowing the external surface thereof to be used as a cryogenic surgical probe.

United States Patent 1191 Sollami et al.

1451 Apr. 2, 1974 1 CRYOGENIC SURGICAL INSTRUMENT [75] Inventors: BlaseJ. Sollami; Thomas J. Bulat; Walter L. Dray, all of Davenport, Iowa [73]Assigriee: The Bendix Corporation, South Bend, Ind.

[22] Filed: Mar. 29, 1972 [21] Appl. No.: 239,088

152 u.s. Cl 62/293, 62/514, l28/303.1

[51] Int. Cl. F251), 19/00 [58] Field Of Search ..'128/303.1;62/293, 514

[56] References Cited UNlTED STATES PATENTS 3,298,371 1/1967 L88 62/2933,427,815 2/1969 PitlOI 62/514 3,477,434 11/1969 HOOd 128/3031 3,696,81310/1972 Wallach 62/514 3,704,597 12/1972 Nicholds 62/514 PrimaryExaminer-Meyer Perlin Attorney, Agent, or FirmLeo H. McCormick, lr.;

William N. Antonis 57 ABSTRACT An apparatus for directly converting agas into a liquid to lower the temperature of a cryogenic surgicalinstrument. A tube with a linear entrance and exit section is helicallywound around a core. A thermal conductive member surrounds the tubebetween the entrance and exit sections. A gas under pressure isconnected to the entrance section of the tube. A sleeve with a closedend frictionally engages and surrounds the thermal conductive member toform a closed chamber adjacent the exit section of the tube. The

. pressurized gas is throttled upon leaving the exit section causing thetemperature in the chamber to be lowered to between 80 to 250C causingthe gas to liquefy. A path through the thermal conductive memher fromthe chamber to the atmosphere will permit thermal energy in thethrottled gas to be dissipated to the pressurizedgas in the tube. Theliquefied gas in the chamber will correspondingly cool the closed end ofthe sleeve allowing the external surface thereof to be used as acryogenic surgical probe.

10 Claims, 6 Drawing Figures CRYOGENIC SURGICAL INSTRUMENT BACKGROUND OFTHE INVENTION Cryogenic surgical instruments have been developed for usein treating diseases wherein other methods would be detrimental to thepatient. These cryosurgical instruments usually have a tip or probewhich is cooled by a low boiling liquid. However, the storage requiredfor low boiling presents a problem to the mobility of the surgicalinstrument.

Later a cryogenic device was developed wherein cooling of the probe wasachieved utilizing the Joule- Thomson effect wherein high pressure gasescool upon expansion. With this device the probe could be cooled to about-80C. At 80C upon touching tissue with the probe, the moisture in thetissue is turned into ice which adheres to the probe. In order toprevent the probe from sticking to tissue, a heating means forinstantaneously raising the probe temperature evolved from necessity.Thus, the operator could remove the probe without injury to the healthytissue. In experimentation where the probe had inadvertently touchedhealthy tissue, cell destruction has been prevented by immediatelywarming the end of the probe. However, the surface cells still would bedestroyed but in the bodys internal repair process of the damaged cellslittle or no scar tissue could be observed. This was attributed in partto the dead cells which were disposed of through the function of thebody.

SUMMARY OF THE INVENTION It was observed that if the temperature of theprobe could be maintained below 80C adherence of the tissue cells to theprobe could be averted. However, to achieve a mobile cryogenic surgicalunit without the problems associated with liquefied gases, it wasconsidered a necessity that the easily stored gas be converted into aliquid upon demand. To directly convert a gas into a liquid between -80to 250C we have devised an appropriate cryogenic apparatus. In ourapparatus a pressurized gas is connected to a tube which is coiledaround a cylindrical core. A thermal conductive material in turnsurrounds the tube and a sleeve with a closed end frictionally securedto the conductive material. The closed end of the sleeve and the end ofthe cylindrical core form a chamber into which the end of the tubeextends. Gas under pressure is throttled into the chamber causing thetemperature therein to be lowered. A path through the thermal conductivematerial will permit the throttled gas to escape to the atmosphere. Asthe throttled gas goes through the thermal conductive material, thermalenergy is absorbed and transferred to the pressurized gas in the tube toinitially cool this gas before it is throttled in the chamber. In thismanner if nitrogen is used as the pressurized gas, the initialthrottling systematically reduces the temperature of the pressurizednitrogen to the point where liquefication occurs upon throttling. Oncethe liquefication has begun, the thermal transfer by the conductivematerial maintains the overall efficiency at an effective level.

It is therefore the object of this invention to provide a cryogenicsurgical apparatus with means to directly convert a gas to a liquidbetween 80 to -250C.

It is another object of this invention to provide a means of initiallycooling a gas under pressure by trans- 2 ferring thermal energy producedby throttling to maintain a portion of the gas in the chamber as aliquid.

It is another object of this invention to provide a cryogenic surgicalinstrument with the means of liquefying different gases corresponding tothe required temperature needed to provide medical treatment.

These and other objects will be apparent from reading this specificationand viewing the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view ofamedical cryogenic system with an enlarged sectional view showing aproposed surgical instrument constructed in accordance with ourinvention. 1

FIG. 2 is a sectional view substantially along lines 2-2 of FIG. 1showing the fluid supply tube surrounded by a thermal conductive member.

FIG. 3 is a sectional view along lines 33 of FIG. 1 showing a top viewof the. surgical instrument.

FIG. 4 is a sectional view of another surgical probe for use in themedical cryogenic system of FIG. 1.

FIG. 5 is an enlarged sectional view of a bimetal strip regulator forcontrolling cryogenic fluid flow through the surgical instrument takenalong lines 55 of FIG. 1.

FIG. 6 is a sectional view of a secondary embodiment of a finnedcryogenic supply conduit for the surgical instrument of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The medical cryogenicsystem in FIG. 1 has a supply vessel 10 containing a suitablepressurized gas. The type of gas is chosen for its liqueficationtemperature, which should be between to 250C, for an example nitrogengas, whose liquefication temperature is l96C. A control valve 12 islocated in the outlet 14 of the supply vessel 10 to regulate flow of thepressurized gas therefrom. A supply line 16 is connected to gage 18which will register the level of pressurized gas flowing from the supplyvessel 10 when the regulator is opened. The gage 18 in turn is connectedto container 20 by conduit 22. The container 20 is filled with achemical dryer, such as lithium oxide or a molecular sieve whereexcessive moisture is removed from the pressurized gas. The container 20is connected to a surgical instrument means 26 by a delivery line 24.

The surgical instrument means 26 consists of a cylindrical core 28 whichhas a front end 30 and a rear end 32. The front end 30 has a shoulder 33which extends from the cylindrical core 28. The rear end 32 has astepped shoulder 34 which extends from the cylindrical core 28 with afirst ledge 36 and a second ledge 38. A series of radial fingers 40extend from the second ledge 38. A central bore 42 in the rear end 32 isconnected by a passageway 44 which terminates between the first andsecond ledges 36 and 38, respectively. A tube 46 has a linear entrancesection 48 which extends through passageway 44 into the central bore 42.The entrance section 48- is sealed in the passageway 44 and the end 50thereof centrally located in bore 42. A jacket member 52 having acentral passageway 56 with a slot 54 is placed around the end 50 of tube48 and between a rearward projection 58 surrounding the central bore 42.A slight taper can be present in the external surface of the jacketmember 52 adjacent the end 60 of the jacket member 52 so that a tightinterference fit will be achieved between the end 50 of the tube and thecentral passage when the end 60 contacts the bottom 62 of the centralbore 42. An additional seal 57 located between jacket 52 and therearward projection 58 provides a unitary structure capable ofwithstanding fluid pressures delivered by the storage vessel to the tube46. The other end 64 of the jacket member 52 retains a male connector 66which engages a female connector 68 on the flexible delivery line 24.

Where the tube 46 emerges from the passageway 44 individually attachedfins such as discs or plates 102, see FIG, 6, or a continuous helicallywound fin 70 shown in FIG. 2 is secured to the tube 46, until reaching apredetermined length. This finned tube 46 is now wound in a coil seriesaround the cylindrical core 28. The fin 70 extends to the shoulder 33and an exit section 72 extends past the end 30 of the cylindrical core28. After the coil series tube 46 is located around the cylindrical core28, a resilient barrier means 74 is alternately wound on the cylindricalbore 28. Sleeve means 76 having an opened end 78 and a closed end 80surrounds the resilient barrier means 74. The resilient barrier meansbeing compressed between the cylindrical core 28 and the internalsurface 82 to frictionally retain the surface 84 of the opened end 78against the radial fingers 40. The radial fingers 40 provide a stop forestablishing a fixed volume chamber 86 between the front end of thecylindrical core 28 and the closed end 80.

MODE OF OPERATION OF THE PREFERRED EMBODIMENT When a surgeon determinescryogenic surgery is necessary to relieve an unwanted tissue condition,he turns the control valve 12 to an open position. The pressure of thefluid (nitrogen for example) flowing from the storage vessel 10 isregistered on gage 18. The fluid passes through the chemical drier whereany moisture therein is removed. This fluid under pressure istransmitted through the supply line 24 into the entrance section 48 ofthe tube 46. The fluid flows around the coil series and emerges from thetube 46 through the orifice 98 of the exit section 72 into the fixedvolume chamber 86. The fluid which passes through the orifice 98 whichhas a smaller cross sectional area than the entrance section 48, goesfrom a high pressure to a lower pressure. This change in pressure isdirectly proportional to the area of orifice 98 as compared to the areaof the fixed volume chamber 82. When the pressurized gas passes from ahigh pressure area to a low pressure area throttling occurs with acorresponding drop in the temperature. The cooled gas can now travelaround the tube 46 over by the fins 70 in a path to the rear 32 ofcylindrical core 28. The fins being thermally conductive will absorbthermal energy from the cooled gas and dissipate this thermal energy tothe gas flowing inside the tube 46. Thus, the gas in tube 46 issystematically and sequentially reduced in temperature to a point wherethe temperature in the fixed volume chamber 82 approaches -196C ifnitrogen is used. When I96C is reached, a portion of the throttled gasis converted into a liquid. The liquid in turn will uniformly distributeits temperature to the closed end 80 of the sleeve means 76. Theexternal surface 88 of the closed end 80 can now probe the damagedtissue and surgically destroy the diseased part.

To maintain the liquid in the fixed volume chamber 86 in anyorientation, a liquid absorbing material 90 is placed in the fixedvolume chamber 86. With the liquid in the chamber being inhibited fromescaping by following the flow path around the tube 46, the surgicalinstrument 26 can be used in any position the surgeon may need. Sincethis instrument is designed to be hand held in order that thetemperature from the body does not affect the thermal transfer betweenthe throttled gas and the pressurized gas in the tube 46, a nonthermalconductive material 92 is placed around the opened end 78. Further, inorder to protect the surgeon, the number of fins around the tube ascompared to the helically wound tube 46 around the cylindrical core areselected such that the dissipation of thermal energy between the fixedvolume chamber 86 and the gas which passes between the finger 40 andsurface 84 will not cause discomfort to the hand of a surgeon if exposedto it over a period of time.

In the embodiment shown in FIG. 4 like parts are numbered the same as inFIG. 1. The tube 46 upon emerging from the passageway 44 is helicallywound around the cylindrical core 28. A screen 94 is placed on shoulder33 and granular particle means 98 poured into the space between surface82 and the cylindrical core 28. The conductive granular particles couldbe bronze coated with a brazing alloy having a melting point below thatof bronze, said conductive granular particles being coated with a fluxbefore placing in the instrument.

When the cavity 100 is filled with this bronze coated flux, thetemperature is raised causing the flux to flow and securely bind theparticles together in a desired configuration. As the gas flows fromchamber 86, the flow paths available will be many since the individualparticles will block any direct flow to the exit 78. The granularparticles 98 will absorb the thermal energy developed by throttling anddissipate the same to the gas flowing in tube 46 as described withreference to FIG. 1.

The size of the fixed volume chamber 86 and the area of the exit section72 construction will vary with the particular gas used in the supplychamber. However, as is apparent when nitrogen gas isused, thepossibility of fire or damage from breathing a pollutant is greatlyreduced. Moreover, in order to conserve the nitrogen supply, a regulator94 whichis responsive to the liquefication temperature in chamber 86 isattached to the opening on the exit section 72. The regulator 94, seeFIG. 5, has a series of bimetal strips 96 attached to a base 98. Thebimetal strips 96 form an orifice 98 through which the pressurized gasflows into the fixed volume chamber 86. As the pressurized gas isthrottled, the bimetal strips will contract to form an orifice asillustrated by numeral 100 when the liquefication of the gas hasoccurred. The bimetal strips being sensitive to temperature change cancontract and expand as needed to maintain the temperature on theexternal surface 88 within a preselected temperature range. Equallyappropriate regulators such as described in U. S. Pat. Nos. 3,517,525,3,590,597, 3,630,047 and incorporated herein by reference could beadapted to control the flow of the pressurized gas. However, we havefound that the bimetal strip regulator 94 adequately controls the flowof pressurized gas to maintain the cryogenic surgical instrument 26within the desired operating range.

We claim:

1. An apparatus for directly converting a gas into a liquid for use incryosurgery, said apparatus comprising:

' a cylindrical core having a front end and a rear end,

said rear end having a series of radial stops extending therefrom;

a tube helically wound around said core having an entrance section whichextends past said rear end and an exit section which extends past saidfront end;

screen means secured to the front and rear ends of the cylindrical core;

thermal conductive means surrounding said tube from said entrancesection to said exit section, said thermal conductive means includinggranular particle means retained between said screen means, saidparticle means contacting each other and said tube, a source of gasunder pressure connected to said entrance section of said tube; and

sleeve means having a closed end and an open end frictionally engagingand surrounding said thermal conductive means, said open end abuttingsaid radial stops to form a fixed volume chamber between the exitsection of the tube and the closed end, said gas under pressure beingthrottled by passing through said exit section into said fixed volumechamber, said throttled gas lowering the temperature in said fixedvolume chamber to between 80 to 250.C by liquefying, said thermalconductive means providing a flow path from said fixed volume chamberaround said tube and out said rear end, said flow path providing anescape route for pressurized gas during said throttling, said flow pathfrom the fixed volume chamber being intercepted by the granular particlemeans causing numerous deflections permitting the granular particlemeans to absorb thermal energy from the pressurized gas flowing alongthe path and to transfer this thermal energy to the gas under pressurein the tube by conductions, said liquefied gas conducting acorresponding temperature to said closed end for permitting the externalsurface thereof to be used as a cryogenic surgical instrument.

2. The apparatus, as recited in claim 1, wherein said exit section ofsaid tube includes:

regulator means responsive to the temperature of the liquefied gas infixed volume chamber for restricting the flow of the pressurized gas.

3. The apparatus,as recited in claim 2, wherein said regulator meansincludes:

a base attached to said exit section; and

a series of bimetal strips attached to said base, said bimetal stripsreacting to the temperature in the fixed volume chamber to formanorifice through which the pressurized gas flows into the fixed volumechamber.

4. The apparatus, as recited in claim 3, whereinsaid thermal conductivemeans includes:

fin means attached to said tube to form a finned section thereon,saidfinned section cooperating with the granular particle means to saidflow path.

5. The apparatus, as recited in claim 4, wherein the length of thefinned section as compared to the length of the helical tube is adequateto dissipate sufficient thermal energy from said pressurized gas toeliminate discomfort to an operator in contact with the entrance sectionof said tube.

6. The apparatus, as recited in claim 5, wherein the external surface ofsaid sleeve means is covered with a thermal non-conductive material toprevent outside thermal energy from affecting dissipation of theinternal thermal energy of said gas by the conductive fins.

7. The apparatus, as recited in claim 1, wherein said source ofpressurized gas passes through a dryer to re-- move any moisturetherefrom which would adversely affect said throttling.

8. The apparatus, as recited in claim 2, wherein said source of gaspasses through a regulator to stabilize the pressure and flow of saidgas.

9. The apparatus, as recited in claim 8, wherein said apparatus furtherincludes:

a liquid absorption material located in said fixed volume chamber toretain the liquefied gas in said fixed volume chamber and allowunrestricted movement of said closed end without loss of said liquefiedgas through said path.

10. The apparatus, as recited in claim 9, wherein the size of the fixedvolume chamber and the exit section of the tube are mated to provideeffective throttling for the source of gas under pressure.

1. An apparatus for directly converting a gas into a liquid for use incryosurgery, said apparatus comprising: a cylindrical core having afront end and a rear end, said rear end having a series of radial stopsextending therefrom; a tube helically wound around said core having anentrance section which extends past said rear end and an exit sectionwhich extends past said front end; screen means secured to the front andrear ends of the cylindrical core; thermal conductive means surroundingsaid tube from said entrance section to said exit section, said thermalconductive means including granular particle means retained between saidscreen means, said particle means contacting eAch other and said tube, asource of gas under pressure connected to said entrance section of saidtube; and sleeve means having a closed end and an open end frictionallyengaging and surrounding said thermal conductive means, said open endabutting said radial stops to form a fixed volume chamber between theexit section of the tube and the closed end, said gas under pressurebeing throttled by passing through said exit section into said fixedvolume chamber, said throttled gas lowering the temperature in saidfixed volume chamber to between -80* to -250*C by liquefying, saidthermal conductive means providing a flow path from said fixed volumechamber around said tube and out said rear end, said flow path providingan escape route for pressurized gas during said throttling, said flowpath from the fixed volume chamber being intercepted by the granularparticle means causing numerous deflections permitting the granularparticle means to absorb thermal energy from the pressurized gas flowingalong the path and to transfer this thermal energy to the gas underpressure in the tube by conductions, said liquefied gas conducting acorresponding temperature to said closed end for permitting the externalsurface thereof to be used as a cryogenic surgical instrument.
 2. Theapparatus, as recited in claim 1, wherein said exit section of said tubeincludes: regulator means responsive to the temperature of the liquefiedgas in fixed volume chamber for restricting the flow of the pressurizedgas.
 3. The apparatus, as recited in claim 2, wherein said regulatormeans includes: a base attached to said exit section; and a series ofbimetal strips attached to said base, said bimetal strips reacting tothe temperature in the fixed volume chamber to form an orifice throughwhich the pressurized gas flows into the fixed volume chamber.
 4. Theapparatus, as recited in claim 3, wherein said thermal conductive meansincludes: fin means attached to said tube to form a finned sectionthereon, said finned section cooperating with the granular particlemeans to said flow path.
 5. The apparatus, as recited in claim 4,wherein the length of the finned section as compared to the length ofthe helical tube is adequate to dissipate sufficient thermal energy fromsaid pressurized gas to eliminate discomfort to an operator in contactwith the entrance section of said tube.
 6. The apparatus, as recited inclaim 5, wherein the external surface of said sleeve means is coveredwith a thermal non-conductive material to prevent outside thermal energyfrom affecting dissipation of the internal thermal energy of said gas bythe conductive fins.
 7. The apparatus, as recited in claim 1, whereinsaid source of pressurized gas passes through a dryer to remove anymoisture therefrom which would adversely affect said throttling.
 8. Theapparatus, as recited in claim 2, wherein said source of gas passesthrough a regulator to stabilize the pressure and flow of said gas. 9.The apparatus, as recited in claim 8, wherein said apparatus furtherincludes: a liquid absorption material located in said fixed volumechamber to retain the liquefied gas in said fixed volume chamber andallow unrestricted movement of said closed end without loss of saidliquefied gas through said path.
 10. The apparatus, as recited in claim9, wherein the size of the fixed volume chamber and the exit section ofthe tube are mated to provide effective throttling for the source of gasunder pressure.